The research plan outlined here is an attempt to determine whether hormonal responses to training modulate (i.e., enhance or impair) memory processing by acting on central biogenic amine systems. In a series of recent studies, the applicant obtained evidence, that if administered soon after training, subcutaneous injections of epinephrine, norepinephrine, or adrenocorticotrophic hormone (ACTH), can enhance or disrupt later retention performance. These results represent the first demonstrations of effects on memory of posttrial hormone injections. The findings of a series of recent preliminary experiments indicate that, across several behavioral and treatment conditions, retention performance is closely related to transient posttraining decreases in whole brain norepinephrine and adrenal epinephrine concentrations. This proposal is designed to confirm these early findings and to examine the generality of the view that hormonally mediated brain noradrenergic responses to training may modulate the storage of new information. In addition, experiments proposed here will examine the possibility that posttraining norepinephrine concentrations predict later retention performance in animals that receive other treatments (e.g., drugs, electrical stimulation of the brain) which impair or enhance memory storage processing.